Description
Mattermost versions 11.7.x <= 11.7.0, 11.6.x <= 11.6.2, 11.5.x <= 11.5.5, 10.11.x <= 10.11.17 fail to authenticate Atlassian Connect installed callbacks, allowing a remote unauthenticated attacker to inject a rogue sharedSecret and disrupt the Jira integration via POST to /ac/installed during the pending-install window.. Mattermost Advisory ID: MMSA-2026-00654
CVSS breakdown
CVSS 3.1
Attack Vector
Network
Attack Complexity
High
Privileges Required
Low
User Interaction
Required
Scope
Unchanged
Confidentiality
None
Integrity
High
Availability
High
Affected products
- Mattermost / Mattermost11.7.0 – 11.7.0
- Mattermost / Mattermost11.6.0 – 11.6.2
- Mattermost / Mattermost11.5.0 – 11.5.5
- Mattermost / Mattermost10.11.0 – 10.11.17
- Mattermost / Mattermost11.8.0 – 11.8.0
- Mattermost / Mattermost11.7.1 – 11.7.1
- Mattermost / Mattermost11.6.3 – 11.6.3
- Mattermost / Mattermost11.5.6 – 11.5.6
- Mattermost / Mattermost10.11.18 – 10.11.18